1. Field of the Invention
The present invention relates to a dial device having operating or displaying elements at the front face of the dial knob and more particularly, it relates to a dial device wherein operating or displaying elements such as switches or display lamps related to the function of the dial knob ar arranged at the front face of the dial knob to make smaller that area on the panel where the dial device is attached and to allow the dial device to be operated with more easiness.
2. Description of the Related Art
Dial devices for achieving various kinds of adjustments such as frequency, level and sound volume selections are conventionally attached to various kinds of machines including measurement and audio machines, for example. These dial devices are intended to achieve the various kinds of adjustments in such a way that amounts of their rotated dial knob are converted to electric signals by the rotary encoder or the like.
In the case of these dial devices, however, the diameter of their dial knob must be made large in order to achieve precise adjustments. In addition, a space for allowing a hand of the operator to operate the dial must be provided around the dial knob and this makes it impossible to locate other switches and the like adjacent to the dial knob. When the dial device of this type is to be attached to the operation panel, therefore, that area on the operation panel necessary for the dial device to be attached becomes unexpectedly large.
The other conventional dial device having double shafts is provided to eliminate the above-mentioned drawbacks. This dial device comprises two shafts arranged coaxial to and independent of each other and two dial knobs attached to the shafts and separated from each other in the axial direction of the shafts. In the case of this dial device, however, the operation of the dial knobs becomes troublesome and there is the possibility of mistakenly rotating the one of the dial knobs while operating the other, because the two dial knobs are separated from each other in the axial direction of the shafts.
In order to reduce that area on the operation panel where one of the above-mentioned dial devices is to be attached, such a means as shown in FIG. 1 is proposed these days. In FIG. 1, numeral 1 represents an operation panel, and dial device 3 is attached to operation panel 1. Numeral 3a denotes a dial knob. Plural function selecting switches 4a, 4b, 4c and 4d are located adjacent to dial knob 3a on operation panel 1. These switches 4a-4d are intended to select the function of dial device 3. When switch 4a is made operative, for example, the dial device functions to set a frequency and when switch 4b is rendered operative, it functions to set a level. Therefore, this dial device can achieve plural adjustments and make it unnecessary to use four dial devices instead, thereby reducing that area on the operation panel where the dial device is to be attached.
However, the plural function selecting switches must be located adjacent to the dial device, thereby making it insufficient to reduce that area on the operation panel where the dial device is to be attached. Various kinds of electric devices have been small-sized these days and operation panels for these electric devices have also been small-sized accordingly. Many operating elements are therefore closely arranged on this small-sized operation panel. This results in that other switches and the like are arranged adjacent to dial device 3 in addition to function selecting switches 4a-4d. This makes it impossible and troublesome for the operator to instinctively recognize which the function selecting switches related to dial device 3 are. Further, one of function selecting switches 4a-4d may be rendered operative because there is the possibility of touching it by hand while operating dial knob 3a. Therefore, switches 4a-4d cannot be located too adjacent to dial knob 3a. As the result, the operator must move his hand more exaggeratedly to operate these knob and switches thereby making it difficult to operate them with easiness.
Although the field of invention is different a little from that of the present invention, Japanese Patent Publication Sho/62- 15375 (which was filed by Nissan Automobile Corporation and made public on Apr. 7, 1987) (U.S. Pat. No. 4,374,310) discloses various kinds of switches and the like arranged on a pad in the center of the steering wheel so as to allow the steering wheel and the various kinds of switches to be operated with more easiness.